Electro-magnetic relays



Marci 18, 1958 M. slMoNs ELECTED-MAGNETIC RELAYS Filed April 8, 1955 nun 5 United States Patent p ELECTRO-MAGNETIC RELAYS Malcolm Simons, London, England, assignor to Telephone Manufacturing Company Limited, London, England, a British company Application April-8, 1955, Serial No. 500,171

Claims priority, application Great Britain May 13, 1954 4 Claims. (Cl. 200-166) This invention relates to polarised electro-magnetic relays and more particularly to the mounting and adjustment of the contacts of such relays.

In such relays, accurate adjustment and maintaining the adjustment of the spacing of the co-operating moving and static contacts are of great importance in the operation in order that the travel of the moving contact and the transit time of the relays may be maintained at a constant value during the life of the relays. It is accordingly the main object of the present invention to enable such conditions to be attained with facility.

Thus, according to the invention, accurate adjustment and setting of a static contact of a polarised relay is provided for by means of a differential screw arrangement in which a hollow member, screw-threaded both internally and externally with threads of somewhat difierent pitches is arranged to be turned for the purpose of the adjustment; the external screw-thread engages a complementary thread in a fixed mounting member while the internal screw-thread engages an axially movable externally screw-threaded member prevented from rotation and carrying or otherwise controlling the adjustment of the static contact. As a result, each complete turn of the hollow member causes an adjustment of the static contact equal to the difierence between the pitches of the two screw-threads.

The hollow member may conveniently be provided with a head in the form of a disc having spur teeth around its periphery which are engaged by the teeth of a small pinion arranged to be turned by a removable key or spanner. The teeth on the disc may pass by an indicator plate provided with a scale or made of a predetermined width, say equal to one and a half pitches of the teeth to enable an adjustment of a predetermined small amount to be made with facility and accuracy.

From the practical standpoint, it is a good thing to hold the hollow member in any given adjusted position. For that purpose, one of the flat surfaces of its head may be engaged by a retaining member which after an adjustment is pressed firmly into contact with the head. The retaining member may thus be carried on a threaded stud which can be turned to move the retaining member into and out of contact with the said head.

The invention will now be more fully explained by describing an example of the novel adjusting mechanism with reference to the accompanying drawings, in which:

Figure 1 is a plan of the static contact support and the adjusting mechanism;

Figure 2 is a central vertical section on the line II-II in Figure l; and

Figure 3 is a sectional plan on the line IlIIII in Figure 2.

The support for the static contact a consists of a rigid mounting arm b of the shape seen in Figure 2. It is provided with a hole tapped with a screw-thread c and in which the tubular adjustment member or sleeve d engages.

The latter is also internally screw-threaded at e where it is engaged by a screw f which carries at its lower end 2,827,535 PateatedMare 18.1958

2 hflistaficrcontacta. The, screw 1?: preuented fromxotating by a metal stripv g whichhas a square hole-h through which a squared part of the. screw f passes. The strip g alsoprovides, the electrical connection to:the contact a an is .clampedrto the arm. b st the anchor ng bol (no shown) which passes through the holesk intothe frame of the relay. As shown, inthe drawing, connection strip g 'is mounted with its plane at right ang les to, the axis. of screwf, whereby the strip rigidly holds the screw against turning about its axis while allowing the screw to move axially with no substantial restraint. The transverse .crimps in the strip reduce the resistance to axial movement of the screw. The strip g has a connection tab 1 at its fixed end.

In a particular example, the pitches of the screwthreads 0, e are such that a complete turn of the hollow member d causes the contact a to be advanced towards or retracted from the moving contact I by 0.0045 inch. The threaded sleeve d has a disc-shaped head m formed with peripheral spur teeth it. These teeth engage those of a small pinion 0 whose spindle is also journalled in the arm b and has an end shaped to be engaged and turned by a removable key or spanner indicated in broken lines at p. As an alternative, however, the pinion may be fastened to the key and is then removable with it.

The teeth n of the head m during adjustment pass close to the edge q of an upturned end I of the arm b and in the example illustrated, the width s of the end is equal to one and a half times the spacing between the points of two adjacent teeth n. By using the two side edges of the end r as reading marks, it will be appreciated that the adjustment can be set to one half the pitch of the teeth n. As there are eighteen of these teeth, the adjustment of the contact a is 0.00025 inch per tooth.

In order to maintain the spacing of the contacts a, 2 when an adjustment has been made, it is necessary to prevent the hollow member d from turning unintentionally. To provide for this, a retaining member is provided arranged to be brought into firm contact with the under surface of the head m. This retaining member consists of a collar 1: on a screw v which is threaded into the supporting arm b. Between the collar 14 and the head m is a thin, sheet metal locking plate w forked at its right hand end at x to embrace the screw-threaded part of the hollow member a. By unscrewing the screw v, the locking plate w can be forced into contact with the under surface of the head m and thus hold the hollow member at against rotation.

I claim:

1. An adjustable mounting for an electrical contact, comprising a rotatable tubular member screw-threaded internally and externally with threads of different pitches and provided with a disc-shaped head formed with equallyspaced peripheral spur teeth, a fixed mounting arm having an internally screw-threaded transverse hole engaging the external threads of said tubular member, a screw threaded into said tubular member and having a contact element carried at one end thereof, means holding said screw against turning about its axis while allowing axial movement thereof, an indicator plate carried by said mounting arm adjacent said spur teeth and serving thereby to give a measure of the amount of adjustment of said contact, and a movable retaining member carried by said arm in a position to be brought into firm contact with a part of said tubular member to retain the latter in any position to which it is adjusted.

2. An adjustable mounting according to claim 1. wherein said retaining member comprises a screw threaded into said arm and having a flange extending into overlapping relation with the disc-shaped head of said tubular member.

3. An adjustable mounting according to claim 1, wherei 3 in said mounting arm is provided with a bearing adjacent the spur teeth on thehead of said tubular member, for rotatably supporting a pinion in driving engagement with said spur teeth. 7 i g 4. An adjustable mounting for an electrical contact, comprising a rigid mounting arm having a threaded hole extending transversely through one end portion thereof and a mounting hole through the other end portion, a sleeve threaded into said threaded hole and being internally threaded at a different pitch from the external threads, a'screw threaded into said sleeve and having a contact element carried by one end thereof, a connection strip electrically connected at one end to said contact element and extending laterally away from said screw parallel with said arm and having a mounting hole formed therein in registry With the mounting hole in said mounting arm, and means connecting said connection strip to said screw to hold said screw against rotation about its axis.

References Cited in the file of this patent Poitras Dec. 28, 1954 

